Air-conditioning systems, such as heating, ventilating and air conditioning (HVAC) system, are widely used in industrial and residential applications. For example, the air-conditioning system can include one or a combination of variable speed compressors, variable position valves, and variable speed fans to the vapor compression cycle to deliver particular amount of heat. The command inputs to the vapor compression system that delivers that particular amount of heat are often not unique and the various combinations of components consume different amounts of energy. Therefore, it is desirable to operate the vapor compression system using the combination of inputs that minimizes energy and thereby maximizes efficiency.
Conventionally, methods maximizing the energy efficiency rely on the use of mathematical models of the physics of air-conditioning systems. Those model-based methods attempt to describe the influence of commanded inputs of the components of the vapor compression system on the thermodynamic behavior of the system and the consumed energy. In those methods, models are used to predict the combination of inputs that meets the heat load requirements and minimizes energy.
However, the air-conditioning systems are known to vary over time. A model that accurately describes the operation of a vapor compression system at one point in time may not be accurate at a later time as the system changes, for example, due to slowly leaking refrigerant or the accumulation of corrosion on the heat exchangers.
In addition, the models of the air-conditioning system often ignore installation-specific characteristics such as room size, causing the model of the air-conditioning system to deviate from operation of the system. For example, the knowledge of the airflow produced during an operation of air-conditioning system can be used to optimize the operation of the system. However, the physical model of the airflow is of infinite dimension and too complex to be used in real time control applications. In addition, the model of the airflow can also change during the operation of the air-conditioning system.
Accordingly, there is a need for a system and a method for controlling air-conditioning system using real time knowledge of the airflow produced during the operation of the system.